| MODEL | TRIUMPH T 120 650 BONNEVILLE 1971 |
| Year | 1971 |
| Engine Type | Four stroke, parallel twin, OHV |
| Displacement / Capacity | 649 cc / 39.6 cu in |
| Bore X Stroke | 71 x 82 mm |
| Compression Ratio | 9.0:1 |
| Cooling System | Air cooled |
| Max Power | 37.3 kW / 50 hp @ 7000 rpm |
| Max Torque | 52.1 Nm / 38.5 lb-ft @ 6000 rpm |
| Ignition | Battery, coil |
| Induction | 2 x 30 mm Amal concentric carburettors |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | Dry sump, double plunger pump |
| Gear Box | 4 speed |
| Clutch | Multi-disc, wet |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | Telescopic forks |
| Rear Suspension | Swinging arm, dual shocks |
| Front Brakes | Drum |
| Rear Brakes | Drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | 181 kg / 399 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.25-19 |
| Rear Tyre | 4.00-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 16 Litres / 4.2 US gal |
| Fuel Consumption | — |
| Top Speed | — |
The 1971 Bonneville stayed at 50 hp from the 649 cc twin. This year Triumph also introduced a new frame that carried the engine oil, though the specification page does not describe it.
